Design, Fabrication, and Integration of Thin-Films for Sensing, Shielding and Power Storage

Transcription

1 Design, Fabrication, and Integration of Thin-Films for Sensing, Shielding and Power Storage Kent Coulter and James Arps Surface Engineering Section Materials & Mechanical Engineering Division Southwest Research Institute San Antonio, Texas

2 SwRI Applications of Thin-films Ion Implantation Tribological Coatings Wear & Corrosion Resistance Impact Resistance Multi-layer Optical Patterns, structures Interference filters Thin-film material EMI shielding Flakes Membranes Catalysts Biomedical

3 Design: Multi-layer Thin Film Devices Application Mechanism Materials Total Layers Sensing Magnetostriction FeCo, FeTb, Fe µm Shielding Coherent Multiple Reflections NiFe, Al2O µm Power Storage Li Ion Transport LiCoO2, LiPON µm Compressive Free Device Thickness Tensile

4 Design: Magnetostrictive Sensor Magnetostrictive Principle CHANGE IN MAGNETIZATION (ferromagnetic) PHYSICAL DEFORMATION/ STRAIN IN MATERIAL CHANGE IN ELECTRIC CURRENT IN CONDUCTOR Operation Modes - Active: Applied current in coil induces time varying magnetic field which in turn generates elastic wave in material; downstream receiving coil measures response - Passive: Use only receiving coil COIL FERROMAGNETIC STRIP Non-Ferromagnetic (or ferromagnetic) Amplitude To Instrumentation FLAWS ELASTIC WAVE System Configuration Time Measured Response

5 Design: Magnetostrictive Sensor Approach Issues/Challenges Activation energy/coupling efficiency - Balance of magnetostriction and magnetization properties - Skin effect/impedance matching (functions of frequency) Elevated temperature - Curie Points - Interdiffusion/Migration Concept: Engineered thin-film a) EXISTING ( mm) COIL Bias Magnet Ferromagnetic Foil/Ribbon b) INTEGRATED THIN-FILM SENSOR (6-8 mm thick) H Planar M Coil Sense Current Alternating layers, each <25 nm, Simple architectures enabling direct patterning Conformable coating technology Benefit Ferromagnetic Thin-film (Aligned) Actuation based on conversion of energy via magnetostriction in ferromagnetic material Engineered, multi-layer composite film Direct integration at surface Use of scaleable vacuum processing methods Increased stability at higher temperature Improved actuation efficiency/lower power Highly non-linear response for efficient, high freq. actuation and simple electronic functions Single layer Engineered Multi-layer Fe/Fe-Tb/Dy Multi-layer Composite Thin-Film Thin-FilmMsS MsScombines combineshigh highdisplacement, displacement,manufacturability, manufacturability,design designsimplicity, simplicity, with with low low power power

6 Design: Shielding High Shielding Efficiency Frequency Specific Lightweight Large Area Stable Cost Effective

7 Design: Rechargeable Power Patch LiCoO2 (high surface area) using PVD processing to create cathode structure Impregnation (solvation) of cation-conducting ionomer, such as Nafion, with lithium ions to form solid polymer electrolyte Engineered porous metal mesh, with copper coating on one side and LiPON coating on other side (in contact with electrolyte) to create anode structure Consolidation of cell structure via hot isostatic pressing to promote flow of electrolyte similar to PEM fuel cell fabrication methods Attributes: Good environmental stability prior to activation; cell activation during initial recharge High power density; rechargeable; all solid state

8 Design: Common Threads Multi-layer Composition Critical Thickness Layer count Film Crystallinity High Stress Surface texture Cost sensitivity

9 Fabrication: Structure Zone Model Angle of incidence Deposition temperature ratio to material melting temperature Energy released on condensation Adatom surface mobility Surface roughness Deposition rate Void coalescence Mass transport and grain growth I Petrov, Department of Materials Science, University of Illinois

10 Fabrication: Vacuum Deposition Atomistic vaporization Solid & Liquid Sources Working Pressure 10-3 to 10-7 Torr Film thickness ,000 nm Rates 1-500nm/s Planar & structured films Metals/Semiconductors: Ag, Al, Au, C, Co, Cu, Fe, Ge, Li, Mg, Mo, Nb, Ni, Pd, Pt, Ru, Si, Ta, Ti, W, Zn, Zr Dielectrics: MgF2, NaAlF6, CaF2, SiO2, SiO, ZnS, TiO2, ZrO2, Fe2O3, WO3, Nb2O5, Ta2O5, CeO2, Al2O3, ZnO, ITO, MgO, DLC, Alloys/ bimetallics: Stainless Steel, Permalloy, Hastalloy, Superalloy TiNx, TiAlNx, SiN, CN, CrSi,

11 Fabrication: Box vs. Web Coating Attribute Box Coater Roll Coater Coating Rate Slow Fast (x100) Coating Angles Planetary Motion Progression of Coating Angles Substrate Handling Sample flat. Not cooled. Coat on curved, cooled drum. Source to Substrate 32 8 Source Occasionally Reloaded Continuousl y Reloaded Base Vacuum 1x10-6 Torr 1x10-4 Torr Left side load roll shaft Right side load roll shaft Right idler Right load cell Coating Control Crystal Monitor Open Loop / Optical Setup Right bowed roll Right nip roll Drum Facing back-door vacuum-side Evaporation Sources web roll coater

12 Ion Implantation/ IBAD Implantation Ion beam texturing and sputtering Surface texture and wettability Gaseous species from H to Kr High-energy ions at 30 to 100 kev, 65mA Medium-energy ions at 1 to 10 kev, 100mA Low-energy ions at 0.1 to 1.5 kev, 300 ma Beams up to 50 centimeters in diameter IBAD Allows control of morphology, internal stress, composition, and density Advantages low temperature process also produces thicker modified regions superior adhesion due to precleaning and ion mixing Experienced with nitrogen, oxygen, carbonaceous species and metals Ion Source Ion Beam Target mixing deposition Atom or Ion Source

13 Integration: MsS Thin Film Development: Magnetic Properties and Thermal Stability Approach Accomplishments (multi-layer composite) Formation of Fe-Co/Fe-Tb multi-layer films Measurement of magnetic response Demonstration of high temperature stability in vacuum and air environments up to 250 oc using xray reflection measurements Other Applications) Actuation/Strain Sensing Energy Harvesting Fe-Co/Fe-Tb multi-layer as-deposited annealed M/Ms Determine effects of processing parameters on magnetic (VSM) and magnetostrictive properties - Composition - Substrate Type (extrinsic strain CTE) - Sputter Condition (Rf bias, power, pressure) - Annealing Measure magnetoelastic coupling efficiency with resonant structures Measure thermal stability of multi-layer films H (Oe) Fe-Co/Fe-Tb multi-layer cps (log a.u.) as-deposited annealed theta-omega (arcsec) 10000

14 Integration: Magnetostrictive Sensor H M Insulating Layers Flux change Sensing Structure Sense Current Magnetostrictive Layers b) 6-8 mm thick Composite Structure - combined giant magnetostrictive/high magnetization multi-layer structure - Reduce magnetic saturation, i.e., field necessary to orient domain structure, - Utilize amorphous films for increased resistance (reduce eddy current) - In-plane easy axis (thin-films) Use of three-layer, magnetic/ insulator/magnetic, for flux change sensing (replace coil) Alternating layers, each <25 nm, (exchange length/ domain width) M Easy Axis H Magnetoresistive films, Easy axis of lower film Perpendicular to top film (bias)

15 Integration: Shielding Coating Process Parameters 1. Load 2 mil PET 2. Coat Al2O3 at 20.0A/s at a web speed of 12.0 ft/min 3. Coat Permalloy at 12.0A/s at a web speed of 10.0ft/min 4. Coat Al2O3 at 20.0A/s at a web speed of 12.0ft/min 5. Repeat Steps 3&4 49 more times.

16 Integration: Shielding

17 Integration: Power Patch - Cathode Objective: Deposit LiCoO2 on Flexible Cu substrate: - Magnetron sputtering from compound targets of lithium metal oxide

18 Integration: Power Patch - Anode Objective: Engineered anode for reversible lithium plating - LiPON (lithium phosphourous oxynitride or similar compound) on foil front-side in contact with electrolyte Status: Initial LiPON coated on Cu substrates

19 Integration: Power Patch Benchmark FIRST Program Excellatron Sample Cell Cell Voltage Elapsed Time (seconds) LiCoO2 Cell on 38mm X 50mm on ceramic substrate. Cell prototype charged using Amel Instruments Model 2059 Galvanostat/Potentiostat. Charge current 0.5mA until cell voltage reached 4.2V (per manufacturer specifications). Discharge using B&K 300W Electronic Load

20 Integration: Power Patch Consolidation FIRST Program Prototype 1 Discharge Curve 2.5 Cell Voltage Elapsed Time (Seconds) LiCoO2 / Li3PO Li+ - Exchanged PEM )2mc/Am( tnerruc LiPON on Cu substrate sandwiched between 0.375" X 3 X3 plexiglass plates Potential (V)

21 Conclusions Multilayer thin film structures result in high performance, lightweight, and robust devices with unique solutions to existing technical problems. Thin film stoichiometry, thickness, and crystal structure can be controlled to utilize the fundamental properties of magnetostriction, electromagnetic permeability, and ion conductivity. By utilizing commercial scale vacuum deposition processes, prototype devices for crack sensors, signal interference shielding and batteries have been developed. Office: Cell: